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Maniphest T76208

Objects referenced in the `UVProject` modifier property are not snapped
Confirmed, LowPublicKNOWN ISSUE
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Description

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 1060 3GB/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 441.66

Blender Version
Broken: version: 2.90 (sub 0), branch: master, commit date: 2020-04-22 19:42, hash: rBf6f4ab3ebfe4
Worked: (newest version of Blender that worked as expected)

Short description of error
When i select an object as projector transform in the UVProject modifier it doesn't snap to the object I added the modifier to.

Exact steps for others to reproduce the error

  • add cube
  • add an empty
  • add uvproject modifier to the cube
  • set the empty as projector transform
  • enable snaping to surface

or

  • open attached file

When moving the empty it does not snap to the cube

bug.blend740 KBDownload

Event Timeline

kookitoo (kookitoo) created this task.Apr 29 2020, 2:52 AM
Alaska (Alaska) added a subscriber: Alaska (Alaska).Apr 29 2020, 3:09 AM

Just to expand. This issue also occurs in Blender 2.82a.

This issue also seems to apply for most, if not all modifiers that require you to select another object. E.G. With the boolean modifier, the boolean object does not support snapping to the object it is modifying. It can snap to other objects.

I can understand why this exists for something like the boolean modifier, and that's because the geometry keeps changing as you shift the object, meaning the snapping points will keep changing. But for something like UV project. I'm not so sure.

Henrik Dick (weasel) added a subscriber: Henrik Dick (weasel).Apr 29 2020, 8:57 AM

That's probably because it would be a dependency cycle. Just imagine snapping the texture coordinate object from a displace modifier to the object that is displaced. It would be very jumpy and would look much more like a bug than just not snapping.

Alaska (Alaska) added a comment.Apr 29 2020, 9:35 AM

@Henrik Dick (weasel) Thank you for your insight. Seems the general conclusion is that this is more of a feature to stop "glitchy" behavior than a bug. I'll leave the final decision up to the developers.

Germano Cavalcante (mano-wii) renamed this task from Every snaping option besides Increment doesn't work when i select the object as a projector transform to Objects referenced in the `UVProject` modifier property are not snapped.Apr 30 2020, 2:20 PM
Germano Cavalcante (mano-wii) updated the task description. (Show Details)
Germano Cavalcante (mano-wii) added a project: Modeling.
Germano Cavalcante (mano-wii) added subscribers: Sergey Sharybin (sergey), Germano Cavalcante (mano-wii).EditedApr 30 2020, 2:24 PM

Thanks for the report, I can confirm.

@Sergey Sharybin (sergey), here another one of those issues in which to avoid a kind of cyclical dependence objects on properties of moficadores do not snap to each other.

Germano Cavalcante (mano-wii) changed the task status from Needs Triage to Confirmed.Apr 30 2020, 2:25 PM
Germano Cavalcante (mano-wii) changed the subtype of this task from "Report" to "Bug".
Brecht Van Lommel (brecht) triaged this task as Low priority.EditedMay 1 2020, 5:52 PM
Brecht Van Lommel (brecht) added a subscriber: Brecht Van Lommel (brecht).

I guess the issue is that we are lacking enough information from the dependency graph to tell us that while the geometry of the mesh does depend on the empty object, it's only UVs so snapping can work. But if those UVs then influence displacement it indeed becomes trickier as well.

I consider this a known limitation more than a bug.

Brecht Van Lommel (brecht) changed the subtype of this task from "Bug" to "Known Issue".May 1 2020, 5:53 PM
Campbell Barton (campbellbarton) moved this task from Backlog to Known Issues on the Modeling board.Sep 21 2020, 1:34 PM